cli: create backups for CRDs and their resources

These backups could be used in case an upgrade
misbehaves after helm declared it as successful.
The manual backups are required as helm-rollback
won't touch custom resources and changes to CRDs
delete resources of the old version.

internal/kubernetes/kubectl/restclient_test.go

@@ -0,0 +1,143 @@
+/*
+Copyright (c) Edgeless Systems GmbH
+
+SPDX-License-Identifier: AGPL-3.0-only
+*/
+
+package kubectl
+
+import (
+	"errors"
+	"testing"
+
+	"github.com/stretchr/testify/require"
+	restclient "k8s.io/client-go/rest"
+	"k8s.io/client-go/tools/clientcmd"
+	clientcmdapi "k8s.io/client-go/tools/clientcmd/api"
+)
+
+const testingKubeconfig = `
+apiVersion: v1
+clusters:
+- cluster:
+    certificate-authority-data: ""
+    server: https://192.0.2.0:6443
+  name: kubernetes
+contexts:
+- context:
+    cluster: kubernetes
+    user: kubernetes-admin
+  name: kubernetes-admin@kubernetes
+current-context: kubernetes-admin@kubernetes
+kind: Config
+preferences: {}
+users:
+- name: kubernetes-admin
+  user:
+    client-certificate-data: ""
+    client-key-data: ""
+`
+
+type stubClientConfig struct {
+	rawConfigConfig     clientcmdapi.Config
+	rawConfigErr        error
+	clientConfigConfig  *restclient.Config
+	clientConfigErr     error
+	namespaceString     string
+	namespaceOverridden bool
+	namespaceErr        error
+	configAccessResult  clientcmd.ConfigAccess
+}
+
+func (s *stubClientConfig) RawConfig() (clientcmdapi.Config, error) {
+	return s.rawConfigConfig, s.rawConfigErr
+}
+
+func (s *stubClientConfig) ClientConfig() (*restclient.Config, error) {
+	return s.clientConfigConfig, s.clientConfigErr
+}
+
+func (s *stubClientConfig) Namespace() (string, bool, error) {
+	return s.namespaceString, s.namespaceOverridden, s.namespaceErr
+}
+
+func (s *stubClientConfig) ConfigAccess() clientcmd.ConfigAccess {
+	return s.configAccessResult
+}
+
+func TestNewRESTClientGetter(t *testing.T) {
+	require := require.New(t)
+	result, err := newRESTClientGetter([]byte(testingKubeconfig))
+	require.NoError(err)
+	require.NotNil(result)
+}
+
+func TestToRESTConfig(t *testing.T) {
+	require := require.New(t)
+	getter := restClientGetter{
+		clientconfig: &stubClientConfig{
+			clientConfigConfig: &restclient.Config{},
+		},
+	}
+	result, err := getter.ToRESTConfig()
+	require.NoError(err)
+	require.NotNil(result)
+}
+
+func TestToDiscoveryClient(t *testing.T) {
+	require := require.New(t)
+	getter := restClientGetter{
+		clientconfig: &stubClientConfig{
+			clientConfigConfig: &restclient.Config{},
+		},
+	}
+	result, err := getter.ToDiscoveryClient()
+	require.NoError(err)
+	require.NotNil(result)
+}
+
+func TestToDiscoveryClientFail(t *testing.T) {
+	require := require.New(t)
+	getter := restClientGetter{
+		clientconfig: &stubClientConfig{
+			clientConfigErr: errors.New("someErr"),
+		},
+	}
+	_, err := getter.ToDiscoveryClient()
+	require.Error(err)
+}
+
+func TestToRESTMapper(t *testing.T) {
+	require := require.New(t)
+	getter := restClientGetter{
+		clientconfig: &stubClientConfig{
+			clientConfigConfig: &restclient.Config{},
+		},
+	}
+	result, err := getter.ToRESTMapper()
+	require.NoError(err)
+	require.NotNil(result)
+}
+
+func TestToRESTMapperFail(t *testing.T) {
+	require := require.New(t)
+	getter := restClientGetter{
+		clientconfig: &stubClientConfig{
+			clientConfigErr: errors.New("someErr"),
+		},
+	}
+	_, err := getter.ToRESTMapper()
+	require.Error(err)
+}
+
+func TestToRawKubeConfigLoader(t *testing.T) {
+	clientConfig := stubClientConfig{
+		clientConfigConfig: &restclient.Config{},
+	}
+	require := require.New(t)
+	getter := restClientGetter{
+		clientconfig: &clientConfig,
+	}
+	result := getter.ToRawKubeConfigLoader()
+	require.Equal(&clientConfig, result)
+}